I'm fairly sure you can submit items to the workshop just fine, you just can't be paid for it. They will keep track of the amount your items earn though, so that if your bank and tax information gets sorted out they will pay you what your items had earned previously.
So, let's say someone does not own a bank account and wants to submit an item to the workshop but they can't because they have to fill out the banking and tax forms. How would they be able to submit their item then if they can at all?